|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
In Reply to: Technical question about vinyl posted by mike_decock on November 18, 2002 at 14:58:41:
Ok, I remember reading the *real* spec. somewhere but have forgotten it now. No matter, I will try to calculate it:If they use electrodeposition to produce the stampers for the 'pits' on the die, then typically the dimensional accuracy for the smallest feature that can be produced is ~0.5 microns (0.5 x 10^-6 m)
Vinyl travels at speeds across the stylus at roughly: 1.6 cm/s to 0.8cm/s (at start & end) - or 0.016 - 0.008 m/s
Thus, the sample rate is approx:
0.016 / 0.5 x 10^-6 per second = 32 kHz at start
and 16 kHz at the end.
(that's for EACH channel of stereo)
Follow Ups:
""If they use electrodeposition to produce the stampers for the 'pits' on the die, then typically the dimensional accuracy for the smallest feature that can be produced is ~0.5 microns (0.5 x 10^-6 m)""I'm confused. I understand pits for cd stamping. Is that the term used for vinyl?
Cheers, John
The stamping process for CDs and vinyl are pretty similar. You have to make a mold with all the bumps & features first, and then stamp it on to the plastic. In the case of pressing vinyl, the bumps can have variable size to make the needle move, but CD pits are of definite size for the 1's and 0's. The molded plastic on a CD is later covered in aluminum to make the pits reflective to the laser.
""The stamping process for CDs and vinyl are pretty similar""Certainly sounds like it..
But isn't the vinyl started by cutting a master, where the wall features (highest frequency limit) are determined by the radius of curvature of the side of the cutting needle? Whereas the CD is photolithography? Or am I (carbon) dating myself?
Course, now that I've posted this, I'll have to google it. Shoulda googled first, but can't open 2 explorers.
If you just minimize (those 3 options, in the most upper right corner) your Explorer, then you can open another session by clicking on your icon in that small panel at the lower left, and swap between them. You only need to have some memory available (anything over 128 MB will do, with W98 SE)At least, it works fine for me: sometimes I go check some data, while writing something like this at AA...
Regards
Use the "New Window" command within IE. You can get there a few was:Click File, New, Window
or
Hold down your Ctrl key and tap your N key. Voila! New Window!
You might also use the Open command from the same menu, along with the previous commands. Whn I see someone add in a website name on the forum but it isn't listed as a hyperlink (in blue), I do the following:
Take the mouse and highlight the link
put your pinkie on the left Ctrl key
tap the C key (copy)
tap the N key (opens new window)
tap the V key (pastes the copied web address)
hit enter.After a little practice, it goes very fast. I think I can open pages faster than popups with thie method! hahaha.
Enjoy!
Thanks. I always wondered what that E down there was for, as I had explorer on the desktop.
It has some neat tabs on top of the navigator window...
I really would recommend IE 6, of your OS supports it. Netcsape, for some reason, just can't achieve the same speeds that IE can. I am not sure why, but it just is.For a low profile browser that doesn't support alot of internet stuff, you might also try Opera. Very, very fast, low overhead.
VE ARE DE GOVERNMENT Ve know what is best. You vill use ONLY government approved softvere!!!Can't do so at work, the IT people try to standardize, but home is a definite possibility.
Is it less vulnerable to hacking? I've '98 se on my home computer with norton antivirus, on a cable modem. Constant hack attack as IP never changes.
TTFN, John
a must with cable modems.
Son of a B. That's exactly what I need. Just can't believe how the prices have dropped.Had a hub, but was afraid to connect to the modem. Routers apparently provide a hard firewall.
I'll be able to connect all 4 of my systems at the same time. It's been a pain, burning 8cm CD's to transfer info. Had a zip, but hated it.
Thank You
;-D
http://eil.com/explore/guide/vinyl_making.asp
but I definitely didn't have any of that sort of information.Building on your comments, the stylus is really only producing musical information when it's direction of travel or speed changes because of irregularities in the groove wall. A totally smooth, unmodulated groove like the lead in and lead out grooves produces no sound at all, or as close to that as possible.
The question then becomes how many changes in travel can you pack into a second of music which is what your calculations address. As you point out it's higher at the start of a side than the end, so the 'sample rate' is always changing.
So, some further questions:
1 - Given that not all music requires as many modulations to the groove wall as can be packed into the space at maximum density, does that imply that the sample rate is lower when the groove wall isn't heavily modulated? and
2 - Given stylus tracking constraints, is there a limit to the density of modulation that can be tracked which is lower than the figure in your calculation and does that imply a lower sample rate as well?
I'll answer my own first question by saying that the sample rate doesn't change because if the sound didn't change, the groove would continue in the same way on the "new sample" anyway. That's on the assumption that this approach to calculating an equivalent is correct, but -I now wonder about this whole approach, however. In digital, the sample rate determines the upper frequency limit which is half of the sample rate since you need at least 2 points to define the wave form. On this calculation for a n equivalent sample rate for vinyl, the sample rate on the inner groove is about half that of the sample rate on the outer groove. While there may be some variation in the upper frequency limit of vinyl between the inner and outer grooves, the upper frequencies on the inner groove don't seem to be compromised by anywhere near that degree in relation to the outer groove and these sample rates, if they were digital, would yield upper frequency limits of 16 kHz for the outer track and 8 kHz for the inner track. Vinyl definitely exceeds both of those frequency limits so I don't think this approach will work at all.
I have to say that the analogy between digital 'bits' on a CD and vinyl 'bumps' on a record breaks down. What we're really doing here, is comparing the highest attainable frequency on a record, to the sample rate of a CD. This only has meaning if we remember the relationship for digital formats where highest frequency = 1/2 of sample rate.While you need 2 digital points to fit wave, the analog format of vinyl means that even on a single 'bump', you still actualy have an infinite number of points to constructing that curve. You could technically say that vinyl has infinite sample rate, but I'm just calculating it on the limit to 'bump' size: ie, the frequency that can be extracted from that feature.
Of course, everything is still dependant on the factors of how fast the stylus can be moved, the electrical connections, etc etc.
.
This post is made possible by the generous support of people like you and our sponsors: